This invention relates to a fuel-injected engine and more particularly to an improved induction and fuel-injection system for an internal combustion engine.
In the interest of promoting fuel economy and effective exhaust emission control, it has been proposed to employ fuel-injection as a means of charge forming. In order to permit the use of lower-cost fuel injectors and longer life and reduced servicing, it has been proposed to mount the fuel injector so that it sprays into the intake system of the engine and preferably into the cylinder head intake passage or a point closely adjacent to it. In this way, the advantages of fuel-injection can be obtained without the problems attendant with direct cylinder injection. However, the use of manifold or induction system injection can present some problems, particularly when running under a widely varying speed and load condition.
For example, when the engine is operated at wide open throttle or high loads, it is desirable to provide a relatively homogenous mixture in the combustion chamber. On the other hand, when operating at low loads and low speeds it is desirable to provide a somewhat stratified charge in the combustion chamber. However, under all running conditions it is essential that there be a stoichiometric mixture at the spark gap at the time of ignition.
Many induction systems are designed so as to provide certain types of turbulence under low-speed, low-load conditions. When turbulence is being generated at low-speed, low-load conditions, it is difficult to maintain stratification of the charge in the combustion chamber. This is particularly true when manifold injection is employed.
Furthermore, many types of induction systems may provide one type of motion in the combustion chamber under one load condition and a different type under another load condition. Thus, fixed fuel-injection systems are not truly capable of ensuring the proper mixture distribution and degree of stratification under these varying conditions.
It is, therefore, a principle object of this invention to provide an improved fuel-injection and induction system for an internal combustion engine.
It is a further object of this invention to provide a fuel-injection system for a manifold injected internal combustion engine wherein the direction of fuel spray can be controlled during engine running and in response to varying load and speed conditions.
In order to improve volumetric efficiency and increase power output, it has been the practice to employ multiple valves per cylinder in an engine. Two intake valves per cylinder are quite common and there is a growing trend toward the use of three intake valves per cylinder. When three intake valves per cylinder are employed, there are normally provided two side intake valves which are disposed closer to a plane containing the axis of the cylinder bore and a third center intake valve that is disposed between the two side valves and further from the plane than the side valves. With this type of induction system it is possible to generate a tumble action from the side intake valves. The center intake valve may generate a reverse tumble which can have a varying effect under the varying speed and loads and can make the problems aforenoted more troublesome.
It is, therefore, a still further object of this invention to provide an improved fuel-injection system for a three intake valve per cylinder engine.